The present disclosure relates to a system and method for supporting large vertically-oriented pumps. More particularly, this disclosure relates to a system and method for vertically supporting a pump and for relieving stress against pump shaft bearings during periods of non-use in a dynamic environment such as the deck of a ship.
To transfer fluids between containers or from one container to a point of use, reciprocating or centrifugal-type mechanical pumps are often employed. Industrial centrifugal pumps consist of a vertically extending column having an intake, and one or more stages of impellers mounted about a shaft at the lower end of the column. The impellers are driven by the shaft, which extends coaxially upward through the column to a drive motor mounted on top of a discharge head, which is mounted on top of the vertical column. During operation, the pump intake is located at the bottom of the pump and is submerged into the pumped liquid or is fed pressurized liquid from one or more feeder pumps. Rotation of the impellers causes the liquid to be drawn into the pump intake delivered to an outlet conduit in fluid communication with another container, conduit, or point of use.
Depending on the particular application, these types of pumps may be of substantial size with typical column lengths of about 15 to about 20 feet (about 4.5 to about 6 meters) or more, and column diameters ranging up to about 3 feet (about 1 meter) or more. The pump is thus made up of several major components, each of which may weigh several hundred pounds, wherein the total weight of the pump can be in excess of about 10,000 to about 15,000 pounds (about 4,500 to about 6,800 kilograms) or more.
As described above, such pumps are generally mounted on a fixed base such that there is little or no movement of the support base while the pump is operating. However, occasionally pumps are mounted on bases that are subject to motion (both during operation and during periods of non-operation of the pump). For example, when the pump is mounted on the deck of a ship, where the ship cants from side to side or comes down hard over the top of a wave. Such motion can impart significant accelerations against the pump and its components—potentially having a G-force of up to about 1.8 G when added to the normal force of gravity. These forces can cause brinneling of the bearings, which significantly reduces bearing life.
In addition, pumps are not currently adequately supported to withstand side-to-side motion or canting of the pump support either during use or periods of non-use.